Sun Dapples

by Carl Strang

Recently I noticed a patch of sun dapples on the trail, and was reminded of a surprising observation from a decade or two ago.

Notice how they all are circular in shape, with fuzzy outlines.

Notice how they all are circular in shape, with fuzzy outlines.

There was a mid-day eclipse of the sun that day, not total but the moon covered a significant percentage. I happened to be where there were patches of sun dapples like these, and as the eclipse progressed I was amazed to see the dapples changing shape. They all were images of the eclipse, at the peak showing little crescent suns.

Warnings had been broadcast in advance of the event, reminding people not to look directly at the eclipse, but to create a pinhole camera effect, holding two sheets of white cardboard, the one closer to the sun with a pinhole in it. The image of the eclipse would be formed on the back sheet, and could be sharpened by changing the distance between sheets. I realized that the tiny spaces between the leaves in the tree canopy above were, in effect, tiny pinholes, and the ground was covered by myriad images of the eclipse. The ground was not the correct distance from the canopy to produce sharp images, but they were clear enough to show the effect. The implication is that these dapples always are giving us images of the sun, as in the photo above.

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4 Comments

  1. jomegat said,

    July 7, 2014 at 6:47 pm

    I noticed the very same phenomenon in 1995. I was on my way to apply for my Master’s Degree (having completed all the coursework). After I noticed the crescents from the dappled light, I noticed another – an inspection sticker on my windshield has a hole-punch to show the expiration date, and that hole was projecting a crescent on the dashboard.

    Ever since, I have been projecting the sun onto whatever surface is handy just by making a tight OK-sign with my hand, and adjusting it until it has nice “pinhole” in it.

    I once went to far as to construct a “solar observatory” by taping a tack-pierced sheet of paper on my office window and observing the sun daily as it projected an image on the opposite wall.

    Way cool!

    • natureinquiries said,

      July 9, 2014 at 6:03 am

      Good stuff, JT, thanks!

  2. Harold Rhenisch said,

    July 8, 2014 at 8:40 am

    Fantastic observation! Thanks for it. What I noticed before is that the harshly pruned chestnuts of Europe cast shadows onto sidewalks which are the models for baroque design. In other words, street design and house design became one and the power of the sun was represented indoors. (In these days in cast iron patio furniture, doormats and, occasionally, still, wallpaper.) But this is just way cool.

    • natureinquiries said,

      July 9, 2014 at 6:05 am

      Interesting possibilities, thanks. Solar inspiration.


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